In Victorian England, Henry Gordon Jago and Professor Litefoot investigate worrying events on the streets of London - which seem to be linked to the New Regency Theatre's resident act, the mesmerist Mr Rees.
London, 1964, and the repercussions of Jago and Litefoot's adventure are dealt with by Sir Toby Kinsella and his crack team of specialists at Counter-Measures. What is the Reesinger Process - and who is behind it?
Disgraced soldiers Ruth Matheson and Charlie Sato are called back into action by Captain Mike Yates, when the UNIT Vault is mysteriously locked down by a deadly force. Together they must infiltrate the Vault and get those trapped out alive. But what enemy are they facing?
The actions of Mr Rees have alerted the Time Lords of Gallifrey, and Romana has assigned her best warrior. Independently, the Sixth Doctor has arrived on Earth. A power from the dawn of the Universe is about to be unleashed once more.